Bioinspired Paste-Extrusion Printed Microlattices with Natural Bone-Like Porosity and Performance.

The structure feature determines its performance. In the field of biological implants, microlattices are commonly used as building blocks for light-weight and adaptive purposes, which however show limitations in biological and mechanical properties as compared with natural bones. Inspired by the efficient mass transfer and high fault tolerance of biological neural networks derived from the hierarchical structure and functional gradient, a bioinspired paste-extrusion printed microlattice (BPPM) structure is developed and its tunable properties are demonstrated. The mechanical properties of non-crossing microlattice structures are first verified outweigh crossing one under equivalent compressive stress. Then, by introducing gradient components and a paste-extrusion 3D printing process, a BPPM structure with a hierarchical porosity, and gradient composites is fabricated. As a result, the BPPM shows the eliminated deformation along the gradient direction, a fine surface roughness (Sa 3.65-15.67 µm), a wide range of porosity (56-78%) and compressive strength (3.44-22.3 MPa), a favorable permeability (3.02 × 10-3.22 × 10D), and good biocompatibility and promoted cell proliferation. This work not only demonstrates the properties of BPPM in a range of natural bones but also provides a robust way to realize it.